Glacier mass balance and its response to 2022 heatwaves for Kangxiwa Glacier in the eastern Pamir: insights from time-lapse photography

Abstract. Contrary to the widespread glacier mass loss in High Mountain Asia under global warming, glaciers in the Pamir-Karakoram region have exhibited anomalously less negative mass balances and even slight mass gains in recent decades. While geodetic studies have quantified decadal-scale mass loss, the process of glacier mass balance and its response to extreme climate events remain poorly understood due to the scarcity of high temporal resolution of mass balance observations. This study analyses the characteristics of daily glacier mass balance during the period from 2019/2020 to 2022/2023 and their responses to the 2022 heatwaves based on time-lapse photography, ablation stake/snow pit measurements and nearby meteorological records collected at the Kangxiwa Glacier in the eastern Pamir. Our results showed that the Kangxiwa Glacier experienced weak mass loss in 2019/2020 and 2020/2021 balance years and significant mass deficits in 2021/2022 and 2022/2023. Observations show that the Kangxiwa Glacier is a spring-accumulation and summer-ablation type, with spring (April–June) accumulation of 200–295 mm w.e. and summer (July–September) mass loss of 306–884 mm w.e. during the past four years. The heatwaves in July-August 2022 caused an abnormal mass loss of over 800 mm w.e. within 40 d, depleting all winter snow accumulation one month earlier than the other three years and driving the equilibrium line altitude above the glacier summit. Characterized by weakened westerly circulation, the 2022 heatwaves led to increased incoming radiation and reduced precipitation. These heatwaves likely affected not only the eastern Pamir region but also the western Kunlun Mountains. Our finding revealed that short-term heatwaves can trigger substantial glacier mass loss in the eastern Pamir, once considered climate-resilient, suggesting that “Pamir–Karakoram” anomaly is increasingly challenged by the growing frequency of extreme heat events.